obile_ in nature
to that of an irresponsible power in a state; and from the effects of a
decrease of a country's corn to the effects of a decrease of its gold
(the utility of which, but not of corn, depends on its value, and its
value on its scarcity). Such, also, were the Pythagorean inferences that
there is a music of the spheres, because the intervals between the
planets have the same proportion as the divisions of the monochord; and,
again, that the movements of the stars as being _divine_ must be
regular, because so are those even of orderly _men_. So, Aristotle and
other ancients supposed perfection to obtain in all natural facts,
because it appeared to exist in some; and so, the Stoics tried to prove
the equality of all crimes by reference to various similes and metaphors
(as, that the man held half an inch below the surface will be drowned as
certainly as the man at the bottom of the sea; and that want of skill is
shown as much in steering a straw-laden boat as a treasure galleon on to
the rocks). But, in fact, the connection by causation between the known
and the inferred resemblance, which is _assumed_ by these metaphors, is
the very thing which they are brought to prove. The real use of such
cases of analogy as metaphors is that they serve, not as an argument,
but as an assertion that one exists. Though they cannot prove, they
sometimes suggest the proof, and point to a case in which the same
grounds for a conclusion have been found adequate. Such are d'Alembert's
classification of successful politicians as either eagles or serpents;
and the statement, as an argument for education, that, in waste land
weeds will spring up; and such is _not_ Bacon's inference from the
levity of floating straw to the worthlessness of the _extant_ scientific
works of the ancients.

The great source of fallacious generalisation is bad classification, by
which things with no, or no important, common properties, are grouped
together. Worst is it, when a word which commonly signifies some
definite fact is applied to other facts only slightly similar. Bacon
(who has himself thus erred in his enquiries into heat) specifies, as
examples of this, the various applications (got, by unscientific
abstraction, from the original sense) of the word 'wet,' to flame, air,
dust, and glass, as well as to water. The application by Plato,
Aristotle, and other ancients, of the terms Generation, Corruption, and
[Greek: kinesis] to many heterogeneous p